ainthorpe landslide north york moors yorkshire march 5 th 1999 louise procter alison pepper
TRANSCRIPT
![Page 1: Ainthorpe Landslide North York Moors Yorkshire March 5 th 1999 Louise Procter Alison Pepper](https://reader031.vdocuments.us/reader031/viewer/2022032200/56649ceb5503460f949b6333/html5/thumbnails/1.jpg)
Ainthorpe LandslideNorth York Moors
YorkshireMarch 5th 1999
Louise ProcterAlison Pepper
![Page 2: Ainthorpe Landslide North York Moors Yorkshire March 5 th 1999 Louise Procter Alison Pepper](https://reader031.vdocuments.us/reader031/viewer/2022032200/56649ceb5503460f949b6333/html5/thumbnails/2.jpg)
What Happened?• A very wet winter in
1998/9
• Heavy rain in the week prior to landslide
• A step in the road of 100mm was found a day or two before March 5th
• Step continued to grow over the next few days to a total height of 1m
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Subsidiary slumps within main soil mass created head scarps and small grabens which break up the road tarmac
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Site Geology• Western Slope of the Coombs• Formed within Jurassic Strata
– Made up of shale and interbedded sandstone
• Ground dips to the North– Valley elevation from 240m to 400m
• Surface material is weathered
– Low heather, bilberry and bracken on the top of the moor
– Grass at the bottom of the valley, previous pasture land
– Glacial till on valley floor
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Timeline of Events
• 1889 and 1929– Previous
landslides formed steps of 250mm;
– After 1929 landslip, a ditch was dug by hand across the moor
• 1980– Motorbike trials on
the moors damaged vegetation cover
• 1989– Bracken reduced
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• 14th Nov 1993– Heavy rain led to
flooding of culvert
• Dec 1993– Second ditch dug to
divert surface flow
• 5th March 1999– 100mm step in road– Increased over few
days to 1m– Movement ceased
after a week
• Summer 1999– Heavy rain could have
caused a second slide
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Possible Prevention Measures
1 Improve and extend existing ditches to take water North of landslide area
→Favoured option
2 Interceptor drains 300mm below the surface
3 Discard and block all ditches & enlarge culvert
4 Increase plant cover to retain water in the soil